BHMT is a byproduct from the manufacture of hexamethylenediamine. Large quantities of hexamethylenediamine are manufactured for use in the production of 6,6-nylon. It is conventional to separate the hexamethylenediamine from other reaction products by distillation. The distillation residue, still heels, contains varying amounts of BHMT, depending on how the plant is running. According to U.S. Pat. No. 4,115,304 to Chadwick, the distillation residue from one hexamethylenediamine plant contained the following amounts of the listed components:
______________________________________ bis(hexamethylene)triamine 5 to 40% by wt C-10 diamine (primarily 10 to 35% by wt 1,4-di(aminomethyl)-1- ethyl cyclohexane) hexamethylene diamine and 2 to 10% by wt adiponitrile poly(hexamethylene)- 30 to 75% by wt polyamines and unknown compounds water trace ammonia trace ______________________________________
BHMT has been reported to have been recovered from such a residue by distillation: see U.S. Pat. No. 3,523,973 to Evans. However, because the BHMT has a high boiling point, attempts to separate it by distillation often lead to degradation and tar formation.
BHMT is useful as an additive in the manufacture of 6,6-nylon. It acts as a "branching agent", and according to U.S. Pat. No. 4,596,742 to Selivansky et al., in a sheath-core nylon yarn, wherein the sheath contains BHMT, the yarn has higher crimp development.
BHMT is also useful as an additive in 6,6-nylon polymers as a dye-receptor, can be added to asphalt to improve the bonding of the gravel to the other components, can be used in paper products, i.e., paper toweling, where it can replace diethylene triamine which acts to improve the wet strength of the paper products.